In the oil and gas industry, it is well known to use slip mechanisms to suspend a string of tubular members (i.e. wellbore casing or production tubing) in a wellbore. Such mechanisms employ a bowl-shaped housing having an axial passage defined there through with a tapered passage wall that narrows toward the lower opening of the passage at the bottom of the bowl. Clamping pieces, called slips, have arcuately shaped inner surfaces sharing a radius of curvature equal or close to the outer circumference of the tubular members of the string to be suspended, and have obliquely sloped outer surfaces tapered at the same angle as the interior passage wall of the bowl. Positioned around the tubular member in the annular space between the tubular member and the bowl wall, the slips gravitationally slide down the wall of the bowl, and the cooperation of the tapered or beveled surfaces acts to direct the slips radially inward toward the central axis of the passage as they fall, thereby encouraging the inner surfaces of the slips against the tubular member. Frictionally engaged against the tubular member in this manner, the weight of the tubular string pulls further down on the slips, with the sloped wall of the bowl thereby further tightening the slips against the tubular member. The tapered wall of the bowl prevents the slips, and thus the tubular member gripped therebetween, from sliding through the open bottom of the bowl, thereby suspending the tubular string from the bowl. As the weight of the slips and the tubular string acts to wedge the slips tighter against the string, the clamping action occurs automatically under the weight of the slips and tubular string.
Due to the significant weight of long tubular strings, the mechanism is typically of a robust design having large, heavy slip pieces, and so the slips are typically coupled to powered actuators of some kind to raise the slips out of the tubular-gripping position when axial movement of the tubular string through the bole is required. However, there are also older patents relating to tools for manually manipulating slips for a tubing or rod string, such as those disclosed in U.S. Pat. Nos. 1,684,974 and 2,260,876.
The applicant has developed new clamping devices sized for use with solid rods, as opposed to larger hollow tubulars, that may employ slip-type arrangements using beveled surfaces to automatically encourage the gripping of the rod, but that additionally are configured to allow use of differently sized slips or clamping pieces for different rod sizes without having to switch to a differently sized housing, and are configured for mounting on a tubing elevator to adapt the same for gripping of rods of lesser diameter than the tubing or casing for which the elevator was intended.